Characterization and control of thermodynamic cloud cavitation

When a liquid experiences a sudden decrease in pressure, bubbles may appear. This phenomenon is called cavitation. If large clusters of bubbles appear, it is called cloud cavitation. Cavitation bubbles can oscillate and collapse rapidly, which can generate shock waves and damage nearby surfaces such as a ship propeller. This project focuses on cavitation in cases where cavitation causes cooling, heating, or boiling. The project will conduct experiments to study and control cloud cavitation. Experiments will use high-speed imaging and acoustic sensing. The results are relevant to a variety of practical applications. These include cavitation in ultracold liquid rocket fuel, in tissue during ultrasound therapy of tumors, and in sonochemistry that uses cavitation bubbles for chemical synthesis. The project also trains graduate and undergraduate students and promotes public awareness of cavitation science. This project addresses cavitation in “thermosensitive liquids.” These are liquids with low heat capacity and liquids near their boiling point. In these cases, heat and mass transfer across the bubble interface dominate bubble dynamics. The hypothesis is that, regardless of the medium or temperature, coherent bubble cluster dynamics (BCD) can be captured by a representative non-dimensional parameter, without the need to track individual bubble behavior. Furthermore, this parameter can be inferred from far-field bubble-scattered acoustic signals. The objectives of the project are threefold: (1) characterize BCD in thermosensitive liquids by optical imaging; (2) correlate BCD with bubble-scattered acoustic waves; and (3) implement control of BCD through acoustic feedback. These objectives are achieved using ultra-high-speed imaging, real-time sensing and signal processing, and data analysis. Project outcomes advance understanding of cavitation and bubble dynamics in various media and under various thermodynamic conditions. The results enhance performance and safety in fluidic systems and devices across various application domains. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2610114 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Kazuki Maeda | Institution: Purdue University, WEST LAFAYETTE, IN | Award Amount: $374,708 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2610114 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2610114.html